/Engine/Source/Runtime/Landscape/Classes/LandscapeTextureStorageProvider.h
Load mip data (used to access preloaded inline mips for creating the initial version of the texture)
virtual bool GetInitialMipData ( int32 FirstMipToLoad, [TArrayView](API\Runtime\Core\Containers\TArrayView)< void * > OutMipData, [TArrayView](API\Runtime\Core\Containers\TArrayView)< int64 > OutMipSize, FStringView DebugContext )